DESCRIPTION: Hydroxyurea Adherence for Personal Best in Sickle Cell Treatment: HABIT The overall goal is to test an intervention to improve the health of children with sickle cell disease (SCD) by enhancing long-term self-managed adherence to hydroxyurea (HU) therapy. Sickle cell disease (SCD), an inherited blood disorder affecting under-served populations in the U.S., is characterized by anemia, painful crises, reduced quality of life (QOL) and high health care utilization. HU is an oral, once-daily medication and sole approved drug for SCD therapy. HU dramatically reduces symptoms, morbidity and mortality, improves quality of life (QOL) and induces increased fetal hemoglobin (HbF) level. HbF has a stable dose- dependent relationship to HU, making it an excellent biomarker to monitor medication adherence. As no uniform HbF target exists, individualized HU-induced HbF levels should reach a stable personal best response to treatment, but often do not. Many youth do not fully benefit from HU due to inadequate integration of daily adherence into their routine self-managed habit. Barriers to adherence may include incomplete knowledge of drug benefit and cultural, logistical and developmental impediments. Challenges specific to HU include limited awareness about benefits and concerns about its safety. Youth also need a developmentally appropriate transition of self-management from their parents. Community-based health workers (CHW) are a well-established partner of the medical home to address barriers through culturally, behaviorally and developmentally aligned intervention. We hypothesize that a unique combination of two established interventions, community-based support for chronic pediatric illness and mobile health communication, will improve self-managed adherence to HU. The specific aims of this 6 month randomized controlled trial are to: 1) Assess the feasibility and acceptability by parents, youth and CHWs of a 6 month intervention of CHW support, augmented by tailored text messages, to improve adherence to HU therapy; 2) Estimate the effect size of the intervention on HU adherence (primary outcome); and on 3) Cooperative youth-parent self-management responsibility, QOL and resource use (secondary outcomes) at 6 months. The goal of this feasibility study is to support the design of a multi-site randomized tria to improve HU adherence through enhanced disease self-management in children with SCD. This research may also inform interventions for other pediatric chronic illnesses in underserved communities.